What do the following two equations represent? $x-y = -3$ $3x+3y = 5$
Putting the first equation in $y = mx + b$ form gives: $x-y = -3$ $-y = -x-3$ $y = 1x + 3$ Putting the second equation in $y = mx + b$ form gives: $3x+3y = 5$ $3y = -3x+5$ $y = -1x + \dfrac{5}{3}$ The slopes are negative inverses of each other, so the lines are perpendicular.